A device for triggering an electromagnetic load, in particular, a solenoid valve, is described in German Patent No. 44 26 021. The load is formed by two partial inductances. The load can be grounded using a switching means. One partial inductance can also be grounded via a second switching means.
This makes it possible to energize only the partial inductance or the entire inductance of the load. When the switching means is opened, very high voltages are generated at the tie point between the inductance and the switching means due to the inductance of the load. Such voltages may damage the switching means.
It is known that a Zener diode can be connected between the tie point between the switching means and the inductance, as well as the control input of the respective switching means, to protect the switching means.
If the tie point between the total inductance and the switching means that controls the total inductance is now connected to a Zener diode, very high voltages are generated when the switching means is turned off. For this reason, Zener diodes with a suitable dielectric strength are required. These are expensive and their integration in an integrated circuit is difficult.